Business Segments - Reconciliation of Assets from Segment to Consolidated (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Segment Reporting Information
Assets	$ 347,412	$ 342,595
Operating Segments | Rail, Technologies, and Services
Segment Reporting Information
Assets	161,121	171,608
Operating Segments | Precast Concrete Products
Segment Reporting Information
Assets	52,371	48,740
Operating Segments | Steel Products and Measurement
Segment Reporting Information
Assets	60,050	58,377
Unallocated corporate assets
Segment Reporting Information
Assets	$ 73,870	$ 63,870